I'm an A and smaller than NYCwoman because my bone frame is smaller.

I don't mind a very thin liner material on a bra I wear for exercising/cycling simply because I do get off and on my bike to do other stuff where there are other people. And I say this even for long touring rides/trips.

I don't wear tank tops with built in bras or anything like that. Nor do I wear cycling jerseys tight/snug/quite fitted across my body. Tight tops make me feel hotter.

I view the very light extra lining...to minimize abit of the "headlights" and also to give even shape.